Regardless of what form symptoms take (SKIN RASH, tingling around the MOUTH, DIARRHEA), a type I hypersensitivity reaction is a systemic response-it affects and involves the body as a whole.
How to Read Your Eyeglass Prescription. The first step to understanding your eyeglass prescription is knowing what OD and OS mean. They are abbreviations for oculus dexter and oculus sinister, which are Latin terms for right eye and left eye.
Key points. 1  Visual field (VF) is a term used to describe how far you can see to the side. 2  Visual acuity (VA) is defined as the clarity of the image seen by the eye. 3  20/20 vision does not mean perfect vision. 4  The term legally blind means different things in different provinces and states.o understand the vision of someone with an eye condition, it can be helpful to know what normal vision is like. Imagine a scenario where two people are sitting on the couch in front of you. If you look directly at Person A, you are able to use your macula, or central vision, to see the details of their head and face.